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The radius of a circle is reduced from 20 cm to 15 cm. The diameter of the circle is reduced by () cm, the perimeter is reduced by () cm, and the area is reduced by () square cm
The radius of a circle is reduced from 20 cm to 15 cm. The diameter, perimeter and area of the circle are reduced by (10) cm, (31.4) cm and (549.5) square cm respectively
The perimeter of a circular playground is 62.8 meters. Later, the radius was reduced by 1 meter. How many square meters was the area reduced?
Outer circle radius: 62.8 △ 3.14 △ 2 = 10 (m); reduced area: 3.14 × [102 - (10-1) 2], = 3.14 × [100-81], = 3.14 × 19, = 59.66 (M2); a: reduced area: 59.66 m2
The length and width of a rectangle are increased by 4cm, and the area of a new rectangle is increased by 124 square centimeters compared with the original rectangle, and the perimeter of the original rectangle is increased
How many centimeters
(a+4)*(b+4)=ab+4(a+b)+16=124
a+b=27
Perimeter = 2 (a + b) = 54
If a square increases its side length by 4cm, the area of the new square will be 112 square centimeters larger than that of the original square. What is the side length of the original square?
As shown in the figure: the side length of the original square is: (112-4 × 4) △ 2 △ 4 = 96 △ 2 △ 4 = 12 (CM). The area of the original square is: 12 × 12 = 144 (cm 2). Answer: the area of the original square is 144 cm 2
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